


Little Sins

by Askellie (NadaNine)



Category: Undertale (Video Game)
Genre: Accidental Stimulation, BDSM, Bondage, Daddy Kink, F/F, F/M, Femdom, Fontcest, Gags, Hurt/Comfort, M/M, Magical stimulation, Masturbation, Multi, Orgasm Delay/Denial, Public Sex, Sensory Deprivation, Size Kink, Tentacles, Voyeurism, edgeberry
Language: English
Status: In-Progress
Published: 2016-07-19
Updated: 2016-08-10
Packaged: 2018-07-25 09:31:57
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con
Chapters: 16
Words: 17,277
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7527499
Author URL: https://archiveofourown.org/users/NadaNine/pseuds/Askellie
Summary: <blockquote class="userstuff">
              <p>A mostly Sans-centric, NSFW collection of drabbles from over on my tumblr. Multiple pairings, lots of AUs, kinks abound!</p>
            </blockquote>





	1. Gaster/Sans; discreet public fingering

**Author's Note:**

> Prompt: Gaster using a magic hand to finger sans under his lab coat during a meeting then fucking him hard after like the possessive sonuvabitch he is.
> 
> Content Warnings: Sanster [Gaster/Sans], pre-game assumed existing relationship (not specifically incest, but you can apply your own headcanons), public sex, fingering, Sans getting pretty rude in Hands.

Sans had an impressive poker face, even for a skeleton. His staple grin was excellent at hiding his real feelings, and he was the sort of easy-going monster who didn’t tend to worked up over anything except the most obscure branches of theoretical physics.

He hardly reacted at all to the first brush of Gaster’s magically conjured hand sliding against his kneecap under the table. In fact, his only response was to turn casually to Roslyn and ask her how her day had been, infuriatingly blasé.

Gaster steepled his fingers, reminding himself that patience was the hallmark of a good scientist. Sometimes you had to wait and alter the experiment to get the results you were looking for.

Sans had been chided dozens of times for his overly casual lab attire to no effect, but right now his shorts gave Gaster nearly unimpeded access. The conjured hand crept deft and spider-like up the length of Sans’s femur. The corners of Sans’s smile turned more ridged, forcibly fixed in place, and the lights in his eyes shifting subtly to glance in Gaster’s direction.

_wat r u doin?_ Sans signed discretely, his hand partially obscured behind an open file. Gaster almost snorted in exasperation, because he’d definitely taught Sans how to be far more articulate with his signing, but Sans often made a point of using sloppy, almost incomprehensible shortcuts. The results were frequently intentionally and unintentionally hilarious. He seemed to enjoy the reactions he could provoke from Gaster, as if their every exchange was some shared private joke.

That was fine. Gaster was learning he liked to provoke Sans as well.

He offered a slight smile – not enough for anyone else to pick up on – and gently tapped an index finger against his mouth in the more universal signal for quiet. Then, nodding graciously as his name was announced for the next report, he rose to conduct his presentation on his latest findings regarding the Core.

If Sans thought he would be granted a reprieve whilst Gaster was occupied, he was sorely mistaken. Gaster was an excellent multitasker, and extremely adept at controlling multiple sets of hands performing independently at once. His own hands were occupied with signing out his findings to the assembled team of scientists. An additional pair were manning the display screen, one directing the controls and a second gesturing to items of interest as he described their meaning to the audience.

His final hand had now come to nestle comfortably in the hollow of Sans’s pelvis, gently stroking each small cleft in the bones of his sacrum. Sans’s eyesockets had gone quite wide, letting Gaster admire the way the lights in his eyes were jittering with his repressed reactions while the rest of his posture was held impressively still.

Though not for long, once Gaster began thumbing the swell of his pubic arch. Small twitches began to show, first in the trembling of his phalanges, then inexorably working their way up his arms. He fidgeted with his notes, perhaps hoping for a distraction, but all his concentration seemed to be going towards keeping himself silent. The rest of the team may have been focusing on Gaster’s presentation with varying levels of interest, but his voiceless speech meant that the room was largely silent but for the occasional click of his fingers. There was no background noise save for the low hum of the air purifiers, and so when Sans suddenly clawed at the table as Gaster found an unexpectedly sensitive plane along the nub of his ischial spine, Roslyn turned to give him an  odd look.

“Are you okay?” she asked, drawing even more attention.

Sans looked aghast. He shuddered briefly, then scrabbled desperately at his coffee cup. “Yeah, uh…t-too much caffeine today.”

Roslyn snorted, and knowing smirks were exchanged by the rest of the team. Gaster allowed himself to smile with them, taking a moment to interrupt the proceedings with the comment, _Really, Sans. You should know better._

_f u_ , Sans signed back vehemently for Gaster’s eyes only, the motions of his fingers sharp and uncontrolled. _f u f u f u_

It seemed to become something of a mantra, because Sans kept it up even as his eyes clenched shut and his teeth ground quietly together, the amusing sight threatening Gaster’s own composure. Thankfully his reports tended to be succinct, and with only a short pause for questions (Roslyn looked like she had one, but she generously swallowed it when Sans gave her a fearsome, hollow-eyed stare) he allowed the meeting to be called to an end.

The others filed out. Sans stayed seated where he was, though that may have been because Gaster’s hand now had a firm grip on the base of his spine, and experience had taught him that action tended to steal all the strength from the shorter skeleton’s legs. A few other members of the team cast curious, askance glances back at the two of them, but Gaster shooed them off with a patient wave until it was only the two of them left in the meeting room.

Once the door was firmly closed, Sans released a shaky, explosive breath. “FUCK, G.”

Gaster beamed and gestured, _As you wish._

Thankfully he still had the additional hands manifested to help support the undersides of Sans’s arms and legs so he could lift his assistant up and push him back over the meeting table.


	2. HoneyMustard; Accidental stimulation

**Notes for the Chapter:**

> Prompt: Accidental stimulation + bruises or other wounds
> 
> Warnings: Fontcest [US!Papyrus/UF!Sans, heavily implied UF!Papyrus/UF!Sans], abusive relationship, Sans having some confused feelings for two people who are pretty much physically and magically identical, wound-tending that turns into ~~badtouch~~ goodtouch.

It was just an accident. His brother hadn’t meant to hit him.

Okay, no, Boss had _meant_ to hit him, just not that _hard_. These idiots didn’t understand what it was like, having as much LOVE as his brother had. It was difficult to control your temper. It made it easy to lash out without thinking. It definitely made it easy to forget that other people might not be as sturdy as you were, and Sans’s extraordinarily low HP was a challenging impediment to work around.

Besides, it was his own fault for not dodging the backhanded swipe, and it was just incredibly unfortunate that Sans had turned to see it coming only at the last moment and had therefore offered it an ideal target in the fragile planes of his eye-socket.

The crack of bone echoed unpleasantly inside his own skull, the shock of the impact more than the force of it sending him stumbling backwards. He might have fallen on his ass if his brother’s doppelganger hadn’t suddenly swooped to catch him, bracing him with careful hands even as he leaned protectively over Sans’s head.

“Dude, what the hell?” Sans had never heard the other Papyrus’s voice snap like that. He usually gave off the impression that nothing could phase him, not even the pissiest of Boss’s moods, but there was a low note of anger in his voice now that made Sans’s spine stiffen even if that ire wasn’t being directed at him. The two Papyrus’s sounding unnervingly similar in their rage.

“That was completely uncalled for!” the other Sans, Blue, exclaimed. By contrast, he didn’t sound _anything_  like Sans did when he was pissed. Blue’s voice got higher and louder rather than lower and guttural, but even if it didn’t sound particularly fearsome it put an amusingly stupefied expression on Boss’s face. Like he couldn’t believe anyone, least of all this tiny, unintimidating scrap of a monster would dare raise their voice at him.

Sans might have laughed, but the moment his expression shifted he felt something warm and wet oozing down over his cheekbone. He reflexively raised his fingers up to touch it. They came away red and gritty, small fragments of bone already turning to dust.

Papyrus leaned closer, staring in dismay. “Shit. Hey bro?”

“Mmm!” Blue nodded, his stance hunched and defensive, like he expected a fight even though he had been very vehement about ‘NO VIOLENCE’ being the primary tenant of this universe. Sans almost wanted to intervene, but from what he’d learned of Blue over the last few weeks was that it was much more likely that Boss was just about to get a _very stern lecture_ rather than an actual beating.

Though Sans wasn’t exactly privy to the nuances of that unspoken exchange between the other two skeletons. He felt almost a little jealous that they just understood each other so instinctively, so naturally, that they could have a whole silent conversation in that fraction of a second and before Sans could figure out what he should do next he found himself unceremoniously hauled up into the other Papyrus’s arms. Boss took a step forward, a snarl of outrage forming in his throat, only to have Blue step resolutely in his path. Sans could do little more than shoot a helpless look over Papyrus’s shoulder as he was carried up the stairs and into Papyrus’s room.

He was still a little shell-shocked from the blow, not to mention flustered by the easy way Papyrus picked him up. No one in this universe seemed to have a concept of personal space. Blue was definitely very physical and clingy, and Papyrus…well, actually he was neither of those things except with his brother. Or with any Sans, apparently, because he’d been uncomfortably touchy from day one and Sans still wasn’t quite sure how he felt about that.

By the time he managed to get his thoughts in order, Papyrus had already set him down on the bed and was staring intently into Sans’s eye-socket. “You…shouldn’t you go watch out for your brother? Boss is still pretty pissed.”

Papyrus gave him a look, like Sans was being an idiot. “You’re bleeding.”

Sans slapped a hand over the injury, grimacing. “It’s fine. Boss-” - _does this all the time_ , he wanted to say, but at the dark look on Papyrus’s face he realised that would be the wrong track to take. “I’ve had worse.”

That didn’t seem to be the right thing to say either. Papyrus firmly pried Sans’s hand away from his face. “Is your eye still working?”

It wasn’t, and when he tried to re-ignite the pupil that had gone out when Boss had hit him, the magic sparked uncomfortably and fizzled out immediately. He grunted in pain, and Papyrus gave him an  _I told you so_  look.

“Stay put,” Papyrus ordered curtly, and went to dig around in his dresser. It didn’t take him long to fish out a first aid kit which he brought back over and began unpacking with startling efficiency. Sans was tempted to comment, but he was too busy straining his hearing to try and figure out what was happening back downstairs. He couldn’t hear anything, and he was tempted to shove Papyrus off and tell him to go check and make sure their brothers hadn’t killed each other (or rather, that Boss hadn’t killed Blue) when suddenly Papyrus gripped his chin firmly, angling his face upwards. “Now hold still.”

Papyrus didn’t usually phrase his requests like orders, which was good or else he’d probably have noticed the way Sans snapped to attention every time he did it. The confusion always followed a moment later, because this _wasn’t_  Boss, it was a stranger and strangers were dangerous and, fuck, now he was sweating from the combination of nerves and familiarity as Papyrus leaned in close and dabbed tentatively at his eye-socket with a pad of gauze.

Papyrus was gentle. His hold didn’t hold Sans trapped. His fingers were rounded and normal, not like the filed tips of Boss’s phalanges, and they didn’t dig into the new fissures around Sans’s eye socket. _It shouldn’t make him feel this way_ , and Sans cursed himself because he could feel the flush of heat in his bones and when Papyrus leaned in, his mouth hovering dangerously close to Sans’s own, and applied more pressure to the ridge beneath his eye. Sans’s body thought it knew exactly how he was meant to respond to this; with a short tremor and a low moan of encouragement.

Papyrus paused. Sans shut his traitorous mouth, hoping desperately that sound might be mistaken for a simple reaction to the pain, but Papyrus was giving him that same knowing, calculating expression Boss sometimes wore and-

_-oh shit._

Papyrus pressed the pad along the underside of Sans’s eye, but the motion was less methodical and more of an exploratory caress and, _fuck_ , he looked so smug when Sans squirmed, his breath coming out in shorter pants even though he didn’t even have lungs that required the oxygen.

“H-hey,” he tried to snap, leaning backwards, but it was hard to ignore the way his soul was doing euphoric tailspins because Papyrus looked like his brother and sounded like his brother and felt like his brother, but also acted in ways completely unlike his brother. In ways Sans sometimes wished Boss would, with his lazy, affectionate grins and the unguarded laughs at Sans’s pitiful attempts at puns and the way he always touched Sans so carefully, but deliberately. None of it was really all that accidental, no matter what Sans had tried to convince himself.

“Don’t worry,” Papyrus said, his jaw lilting in a lop-sided grin. “I’ll be gentle.”

That wasn’t the point, and not even what Sans really wanted – if he even wanted _any_ of this – since he liked it when Boss was rough and didn’t treat Sans like he was made of glass, but it was comforting to be reassured. Boss never did that. He definitely wasn’t _gentle_.

He’d never made Sans come undone quite like this – with a tingling thrum of magic on his fingertips, sinking into the cracks of his eye-socket with the aching itch that both soothed and stimulated. Sans found himself unconsciously rocking into Papyrus’s hands, trying to force pressure against all the places that were most tender, but with each stroke the hurt started to subside and there was less to distract him from how nice the touch was simply for its own sake.

Papyrus changed his grip, large hands on either side of Sans’s skull, pulling him closer, and Sans had only a moment to think, _fuck, he’s going to kiss me_.

Except Papyrus didn’t kiss him. At the last moment he angled Sans’s head downwards, and Sans only caught the reflected glow of his conjured tongue before it was lapping at the rim of his eye-socket, wet and hot and almost unbearable against sensitive, newly healed bone.

“Oh shit.” He gripped the front of Papyrus’s hoodie, hands clenching spasmodically. “Shit, yes, _god_ -!”

He wasn’t even thinking. Who the hell could think when there was a tongue probing around in their eye-socket!? He was pretty sure most other monsters would find it as disturbing as fuck, but to Sans it was exactly the right kind of discomforting intimacy that got his bones rattling and he could feel the reverberation of chuckling amusement through Papyrus’s mouth and where the bones of his teeth clicked against Sans’s eye he felt twinges of pain that made his spine want to arch up for more.

'More’ was not forthcoming, however. Papyrus gently pushed him back onto the mattress – he’d half-crawled into the taller skeleton’s lap – and seemed to take a moment simply to admire the dazed, intoxicated expression Sans was wearing.

It was a very unwelcome moment for the door to be suddenly kicked open.

Sans blinked owlishly, watching Boss’s expression twist from disgruntled ire to suspicious consternation as he looked between Sans and Papyrus. “What the hell are you doing?”

Papyrus flicked him a lazy glance. “Did Sans sent you up to apologise?”

“Yes,” Boss ground out after a moment of hesitation, looking even more displeased that his own question had been ignored. Sans was still too busy gaping or he would have been amazed at the sort of miracles his cross-universe counterpart had wrought.

“And…?” Papyrus gestured vaguely.

“And you can get your filthy hands off my brother and get out,” Boss hissed, stalking over…or, he tried to, but after two steps he was pulled up very suddenly by a soft _ting_. From inside his armour, his soul burned blue with Papyrus’s magic.

“That doesn’t sound like an apology,” Papyrus noted, and with an infuriatingly casual wave of his hand, he tossed the other skeleton back out of the room again. “You can come back when you’re ready to try again.”

A shriek of fury was cut off as an equally negligent flick of magic slammed the door shut. Sans was starting to think it might have some kind of magical sound-proofing. It tremored, as if hit with force from the outside, but no further interruption was forthcoming.

Sans felt stunned. And lost. And still confusedly aroused. He tried to articulate this, but all his mouth came up with was, “He’s going to kill you, you know.”

Papyrus’s answering smirk was surprisingly unsettling. “Let him try.”

He turned back to Sans, his expression gentling slightly into more of a playful leer. “Now. Where were we?”


	3. Underfell Sansby; Love and Money

**Notes for the Chapter:**

> Prompt: Underfell Sansby, Sans paying off his tab.
> 
> Content Warning: Sansby [Underfell Sans/Underfell Grillby], consensual prostitution, dominance/submission, withholding gratification. Sans would have you believe he doesn’t enjoy any of this, but he doth protest too much.

The kitchen was always stiflingly hot. It made the sweat on Sans’s bones prickle oddly, made him feel blatantly aware of his nakedness under his clothing in ways that were downright discomforting. He hated this. He didn’t want to be here.

_If you really didn’t want it, you’d stop_ , a singsong voice rang through his thoughts. _You’d stop coming to the bar, stop eating the food and drinking the mustard, stop racking up that tab…_

Hell, if he really had a problem with it, he could probably talk Grillby into some other form of payment. The fire elemental was well-connected, and had no shortage of contacts who needed things done, needed problems solved, needed all manner of unspeakable acts committed…

This was easier, he convinced himself. He could even believe he was lucky, sometimes. There were worse things - indescribably worse things – that Grillby could have asked for.

Most of his requests were almost laughably simple.

“Strip,” Grillby ordered, sounding almost bored as he leaned back against a counter, watching Sans with hooded eyes as the skeleton shifted restlessly from foot to foot.

The command was almost a relief. Sans’s thick jacket was fine for outdoors, but in here it was too heavy, practically suffocating. He shrugged it off, not caring that it fell onto the floor. Grillby kept his kitchen more pristine than even the bar. Here, everything was cleansed with fire, and he didn’t have to worry about much more than the occasional smear of soot.

Grillby watched him undress, his expression growing incrementally more smug with each article of clothing removed. For someone who should have embodied the stereotype of being hot-blooded, Grillby liked to take an inordinate amount of time getting into things. In the beginning, that had made Sans nervous as hell. He’d thought Grilby drew it out just to get a kick out of watching him suffer. He’d tried to convince himself to be grateful, since more time dicking around meant less time actually being touched and having to do things, but now it just made him annoyed and kind of impatient. The touching thing he’d gotten used to. He was ready to get down to business.

_Come on, Grillby, just fucking do it already._

“Down on your knees,” Grillby said, idly resting a chin on his hand. His voice was never very loud, and Sans had come to understand that a lot of elementals had trouble with common speech. Their language was a lot more complex, articulated in form and movement and the shape and colour of their bodies. Most of the elementals had died in the war, being some of the most powerful creatures in the Monster kingdom. Many more had perished in the underground before finding environments that could perpetuate their ethereal bodies. Only the strongest had lived, and those that had were usually viciously territorial against the intrusion of others of their kind, lest their dwindling resources be stolen.

A lot of people speculated that Grillby had learned to speak common in defiance of his natural disadvantage simply so he’d still be able to talk to people, given how avoidant his own kind were. Sans sort of thought it had more to do with power; sure, Grillby’s voice didn’t have a lot of force, but when he used it, people listened. Sans’s own body always jolted a little at that strange crackling hiss that accompanied Grillby’s speech, especially when it was being directed solely at him.

_Come on, come on, get over here, I’m ready._

“You look good like that,” Grillby offered, and Sans flushed, turning his face towards his folded knees. It was always weird as hell when Grillby brought out the compliments. Even thought Sans was half-sure they were meant to be mocking (though the tone wasn’t quite right for that) he could never help the small squirm of gratification. With Boss hounding him every day with all of Sans’s immeasurable failings, both real and imagined, it was nice to hear something to the contrary every once in a while.

Grillby waited until Sans looked up again, then crooked a finger at him. “Come here.”

Sans’s indignant bristling was more for show than anything. He knew exactly what Grillby wanted, and grudgingly crawled across the floor, his progression slow and awkward, kneecaps clicking on the floor.

“Why you always gotta be such a dick about this,” he grumbled under his breath, shuffling forward until he was crouched at Grillby’s feet. He reached up automatically, going for the elemental’s belt, but Grillby caught his wrist.

“Now, Sans. I didn’t ask for that.”

“Oh come on,” Sans said, and to his own aggravation, there was a bit of a whine in his voice. “Let me just-”

He reached up, trying to free his wrist, and Grillby caught his other hand too, pinning them easily with no apparent effort. Sans hissed, writhing a little, but didn’t make any serious effort to escape. He wasn’t supposed to do anything Grillby didn’t ask for. He shouldn’t even want, to, but-

_Fuck! Fuck you, just fucking touch me, I need it._

Grillby held him like that for a minute, just watching Sans snarl and spit like a thwarted kitten, and then smoothly shifted his grip and lifted Sans up onto the counter beside him. Sans blinked at the change in position, finding himself perched on the edge, Grillby standing between his open legs. Grillby pressed close, and his body was so unbearably hot, his edges thrumming with magical flame. Sans opened his mouth, panting, and found it suddenly invaded by a searing tongue as Grillby tilted his head back and kissed him.

He moaned, feeling Grillby’s mouth scalding the bone, almost too-intense even as most of his pent up tension began melting from his spine. He was okay for about a minute, happy to let Grillby dominate every corner of his mouth and fill his skull up with dizzying heat, but when Grillby’s hands came to rest almost chastely on his hips with no apparent intention of moving any time soon, the kisses turning slow and lazy and sensuous, he grumpily hammered a fist on the elemental’s chest until he could untangle their tongues and free his mouth to speak.

“Fuck! Stop that!” He was blushing harder now. Fucking Grillby and his fucking slow-ass, weirdly sentimental kinks. “Come on!”

He yanked Grillby by the tie, throwing all his weight backwards so the elemental would be pulled against his chest, their groins grinding together with new friction. Sans was at the perfect height for this, and he swiftly clinched his legs around Grillby’s waist, clinging tightly and rubbing against him enticingly.

“See, look, I’m fucking here, you can stop screwing around any time!” He managed to get his arms around Grillby’s neck too, clinging for dear life as he undulated his spine, frotting desperately against the front of Grillby’s dress-slacks. He always looked so fucking perfect, even after a long day of cooking, and Sans would have thought it was brutally unfair if he could think of anything at all except how much he hated being teased. “Grillby-!”

Grillby laughed, letting him get away with it for a minute before reluctantly peeling Sans off his front, pushing the skeleton back down onto the counter. For a moment, Sans giddily thought this might be it, and eagerly spread his legs. Grillby looked him in the eye, taking a moment to visibly hold himself in check, and then grinned. Positioned as he was, Sans could see the hazy shape of fangs between Grillby’s lips.

“Sans,” Grillby’s tone was admonishing. “You worked up a lot on your tab this month. Stop trying to cheat your way out of it.”

Sans made a wheezing, disgruntled sound that wasn’t quite a protest. Grillby tapped him chidingly on the side of his skull.

“Hold still. I’m not nearly done with you.”

Fucking hell. If they were going at Grillby’s pace, Sans probably wasn’t going to get out of here until some ungodly hour of the morning. And, stupid smitten idiot that he was, Sans was probably going to hate enjoying every minute of it.


	4. Soriel; Femdom and Voicekink

**Notes for the Chapter:**

> Prompt: Soriel, with sexyteims happening across the barrier of the door.
> 
> Content Warnings: Soriel [Sans/Toriel], Fem dom, mutual masturbation in a public/exposed setting, voice kink, anonymity, fantasising.

“Are you ready?”

Sans leans back against the door and feels the returning pressure from the other side. This is the closest they can get to touching, but her voice wraps around him with a pleasant, sultry weight. His breathing quickens. “Yeah. Definitely.”

She makes a pleased sound, soft and deep. “Then I would like you to remove all of your clothing.”

 _All of it?_ He almost echoes, but doesn’t. He doesn’t want to sound incredulous or, worse, unwilling. He hesitates for a moment, but it’s mostly to master the tremble of excitement in his fingers before he shrugs his jacket off his shoulders. The t-shirt goes next. He tries too exaggerate the movements as much as possible. It’s not very easy to undress loudly, but he does his best so she can hear the removal of clothing through the door and know that he’s obeying her. It doesn’t take long before he’s kicking off his slippers and socks, and then he’s standing naked in the snow, entirely exposed.

“Very good,” she purrs, and the approval in her voice makes pleasure unfurl in his chest. “How do you feel?”

“A bit chilly,” he admits, because he promised her he’d be honest. That’s the second promise she’s coaxed out of him. It’s getting harder to deny how completely smitten he is. “It’s snowing out here, you know.”

“Oh my,” she says, though it’s more playful than sincerely concerned. He’s told her in the past that the cold isn’t really dangerous to him. “Well we’d best ensure that you stay warm, yes?”

“Yes,” he agrees, letting his eyes glaze a little as he presses back against the barrier that separates them. Without clothing to shield him, its surface is hard and icy, but he can almost feel the coiled warmth of her presence behind it.

“Reach down,” she orders, and god, he’d thought her voice was nice when she was giggling around an awful pun, but when she commands it’s strong and imperious and makes him a little weak in the knees. “Touch between your legs. Tell me how it feels.”

He complies, feeling the spidery touch of his own phalanges resting on the curves of his hips before sliding them lower. “A-ah…it…”

He doesn’t want to get too specific. They still haven’t exchanged names, and he doesn’t want to break the comfortable anonymity they have by describing himself even though from the number of bone-related jokes he’s told, she might have guessed already. Still. “It’s been a long time. I’m…pretty sensitive. It feels new, and unfamiliar. Almost like it’s the first time.”

Behind the door, he can hear a shuffle of heavy fabric as he guesses her own clothing is moved out of the way. He rattles audibly before he can control himself, imagining her in the vague, shapeless shadows of his mind; curvaceous and soft and shamelessly cupping a breast as she listens to him.

“Can I…put a finger inside?” he asked, rocking slightly into his own touch, gripping tightly at the curves of his ischium so he wasn’t tempted to progress without her explicit approval.

“Not just yet,” she says, sounding a little breathless now. “I want you down on your knees.”

He groans aloud, complying. His shins hit the snow with a soft thump he hopes she can hear.

“Now bend forward,” she continues. “Press your face into the ground. Lift your hips high.”

He hadn’t thought simply following direction could be so erotic, but the position she’s demanded of him is blatantly wanton. If she could see through the door, his ass would be presented to her, and the thought makes him groan again, fingers scrabbling on bone. “Now?”

“Yes, dear,” she agrees, and he isn’t sure if it’s the endearment or the way her own voice quavers with rising pleasure that makes him whine as his fingers curl into his pubic cavity. He lets out a short wail as he grinds down, fucking his own hand with reckless abandon.


	5. Swapcest with Fell!Sans

**Notes for the Chapter:**

> Content Warnings: Swap!Pap/Swap!Sans/Fell!Sans, polyamory, partner sharing, sloppy make-outs, heavy petting, oral sex for souls, so much fluff. ALL THE FLUFF. The fandom needs more of this trio, I swear.

“I don’t mind,” Blueberry said suddenly, apropos of nothing.

Well maybe not _nothing_. Red had been ignoring the TV in favour of staring up at Papyrus’s room, wondering if its usual resident was home yet, and whether he would want to join them for Napstabook’s current musical marathon. It was a ridiculous, sentimental notion he wouldn’t have thought himself capable of, but he liked it best when he could fall asleep sandwiched between the two other skeletons, listening to their playful bickering and teasing.

Red jolted guiltily. “What?”

Blue gave him a patient look, tempered with kindness. “I don’t mind the way you look at my brother.”

Red spluttered, blushing furiously, ready to object that he most definitely did not look at Papyrus in any noteworthy way, but lying to yourself was particularly difficult when faced with an actual cross-universe doppelganger wearing an extremely knowing expression.

“I don’t-! I mean, I wouldn’t-!” Blue just arched an eye-ridge, and Red buried his face in his hands wishing he could smother himself out of existence. “Fuuuuuuuuck.”

Blue laughed. “I just told you, I don’t mind. I get it. I love Papy too!”

The way he said that, so easily and freely, almost made Red a little jealous. Blue’s eyes literally lit up when he was thinking of his brother the way he was now, with warmth and tenderness.

“You should mind,” he mumbled into his hands, because it was only the truth. Red wasn’t an idiot. He was usually awake on the nights when Blue would creep out of his own room and into his brother’s. He’d walked in on a few awkwardly aborted sessions that had probably been fondling or kissing right before he’d entered the room. Papyrus and Blue were already a thing. Red had no place there.

“Well I don’t.” Blue scooted closer on the couch, pulling Red into a now familiar, comforting embrace. Blue was a very tactile creature, and very easy with his affection and forgiveness. Red didn’t even put up much of a fight any more, sinking against the other Sans with only a slightly disgruntled expression as he reluctantly accepted the reassurance.

They stayed like that for a minute, Red feeling all the uncomfortable tension and embarrassment slowly seeping out of him, until Blue suddenly piped up again, “I don’t mind the way you look at me sometimes either.”

Red stared at him, mortification returning in an instant. He couldn’t utter so much as a squeak as Blue smiled cheekily, his arms around Red tightening meaningfully as the embrace suddenly took on a very different connotation. Very carefully, Blue nuzzled against his cheek, bone gently scraping against bone. Red quivered, bones rattling from nerves and excitement and far too many feelings.

_Shit shit shit!_ Even that gentle, chaste contact had him pressing harder into Blue with a soft sound of confusion, because surely he was just dreaming this, it was like some stupid, desperate fantasy his brain had conjured up because he was still lonely and needy and hungry for attention despite the brothers treating him more kindly than he’d ever deserved in his entire shitty life-

“Am I interrupting?”

The evening was turning into an almost comedic sequence of heart-attacks for Red, but Blue seemed nonplussed at the sudden appearance of Papyrus on the upper landing. The taller skeleton was smirking down at them, looking unperturbed at what had most definitely been an inappropriately intimate display. Red squirmed, feeling positively reprehensible, but Blue just held him more tightly.

“Not at all!” Blue called up, sounding as cheerful as he ever did. “I was just having that talk with Red. I think it’s going well!”

“Ah,” Papyrus said, making his way down the stairs at a leisurely pace. “Mind if I join you, then?”

Blue made a show of considering, his fingers moving in a distracting way down Red’s ribs. “Sure! I don’t think Red minds, right?”

Red made a completely incomprehensible sound that most likely translated to, _what the actual fuck!?_ but it wasn’t an obvious ‘no’ so Papyrus plopped down on Red’s other side, sending a ripple of the impact along the cushions. Red found himself boxed in between two intensely focused skeletons, and for all he’d scoffed about how soft and harmless the brothers were, he felt absurdly intimidated. He shrank back into the couch, but there was really no place to hide. It didn’t escape his notice, though, how loose their hold on him was. If he’d really wanted to get free, he could have.

He just didn’t want to.

Papyrus took hold of his chin and gently tipped it upwards. He took a moment to just drink in whatever expression Red was wearing, his grin taking on a more lascivious cant. “May I?”

Red made another sound, this one more of a whimper but still not a 'no’, and that was apparently permission enough for Papyrus to press their teeth together in a skeletal kiss. For a moment they just stayed like that, enamel clinking softly against enamel, and then Red tilted his head and let his tongue creep out to graze invitingly against Papyrus’s incisors and suddenly the kiss turned into an urgent, wet mess of licking and grinding and fervent groaning and Red was melting in pleasure.

“Hey!” Blueberry objected, indignant. “No fair! I wanted to do that first!”

Papyrus pulled back slightly, coming up for air. “Hah. Sorry, bro.”

Red didn’t have a moment to think before his skull was dragged back towards Blue. The other skeleton held both sides of Red’s jaw, beaming at Red’s flustered features before apparently doing his best to ensure that just because he came second, his kiss would be no less memorable. Red was a little taken aback by how forward his normally sweet-natured doppelganger was. Blue’s tongue swirled deftly against his, exploring the deeper recesses of his throat until Red was dizzy and trembling. When Blue finally released him, there was a fetching shimmer of colour across his cheekbones, and an extremely proud glint in his eyesockets.

One of Red’s knees had somehow ended up slung across Papyrus’s lap. He couldn’t figure out where to put his hands, but Papyrus solved that for him by guiding them up over his head and pinning them loosely against the backrest of the sofa, giving the two brothers unimpeded access to Red’s rib bones and spine. Three eager, pawing hands made their way under his shirt, mapping out the places that made him writhe and groan while his eyes rolled back in his skull. He could hardly concentrate. The moment Blue had ended his kiss, Papyrus had dragged Red back for another one, and Red found himself being traded back and forth between the brothers for every possible exploration of his mouth. Slow and sensual. Demanding and hungry. Playful and teasing. Back and forth, until Red’s head was spinning and his breath came out in wet, panting wheezes.

An unfamiliar pressure formed behind his sternum. Red barely even noticed it beneath the haze of bliss until Blue suddenly spoke up. “Oh Red…it’s your soul.”

It had coalesced entirely without his intent. How embarrassing. Red whined, tugging weakly against the hold Papyrus had on his wrists, but apparently his struggle for freedom wasn’t convincing enough because the taller skeleton didn’t loosen his grip.

Blue drew his hand back, but Red’s soul followed it like an eager puppy seeking attention, making Blue chuckle in delight and even Papyrus gave a low snicker.

“Can we touch it?” Blue asked softly, looking earnestly into Red’s eyesockets. God. That face. No wonder Papyrus could never say no to his brother. Red couldn’t even think of the last time he’d let anyone touch his soul, for pleasure or otherwise, but there was no denying the way the stupid thing was trying to shove its way into Blue’s gloved palm. Souls were too honest, and his apparently didn’t have any sense or dignity whatsoever.

He clinched his eyes shut, and gave a tight nod.

“Hey, bro, I have an idea,” Papyrus said, gently placing his hand alongside Blue’s, cupping the soul and lifting until it rested beneath them. “Help me with this.”

He leaned forward, mouth opening, orange tongue snaking out, and Blue apparently understood immediately because he mirrored the motion. Each of them claimed a side of Red’s soul, tongues laving  against the thrumming surface, and each jolt of pressure made Red gasp. He watched with wide eyes as Papyrus lifted his free hand, cradling the back of Blue’s skull with familiar tenderness, and then with a sudden jolt he dragged his brother forward, crushing their open mouths together with Red’s soul still trapped in between them.

“FUCK!” Red shrieked, nearly convulsing out of his seat, but the brother’s were leaning across his lap now, keeping him thoroughly trapped as they licked and sucked at his oozing soul between equally sloppy kisses. Blue was humming in pleasure, and the vibration thrummed through Red’s soul with each note. Papyrus’s tongue was longer, and deft enough to curl around his core with slow, constricting squeezes that made Red burble incoherently and left him unable to do anything except melt bonelessly into the couch.

The pleasure went on forever. It built in waves of heat and slick friction and clenching swallows around his soul until Red’s vision burned with a blinding white haze and blissful extract had him collapsing deliriously into waiting arms. He was barely cognizant of his dripping, satisfied soul being ushered back into his chest cavity, stroking hands gently petting and coaxing him back from the overwhelming climax.

“I think he liked that,” Papyrus remarked, sounding far too smug.

“I don’t know,” Blue hedged playfully. “I think we can do better, don’t you, brother?”

Red suddenly wondered if he really understood what he’d just gotten himself in to.


	6. Fellcest/Swap!Pap; petplay

**Notes for the Chapter:**

> Content Warnings: Fell!Papyrus/Fell!Sans/Swap!Papyrus, petplay, soul play, dominance/submission, voyeurism, humiliation. All very consensual!

“Sans.”

Sans sits back on his heels, spine straight, his attention completely focused on his brother. Papyrus doesn’t smile, but there’s an appreciative softness in his eyes that’s almost as good.

“Submit.”

Sans closes his eyes, and with that simple order his body goes slack, all tension and resistant melting out of him instantly.

“Huh,” Stretch says, intrigued. “Nice trick.”

“He’s well trained,” Papyrus said sternly. Sans feels a pull in his chest, and makes only a soft cry of sound as his soul is deftly pulled from his body. “Not that you would know since you seem to have no idea how to treat my brother properly.”

“Then teach me, oh mighty one,” Stretch grumbles peevishly. Sans wants to step in, wants to nudge Stretch in the ribs and share that knowing eye-roll that makes them both more tolerant of Papyrus’s blunt admonishments, wants to give his brother that beseeching look that reminds him to tone it down for a change, but right now he’s not in a position to do anything except what his brother demands of him.

“I will,” Papyrus replies primly, either ignoring the mocking tone or oblivious to it. He holds up Sans’s soul and, without ceremony, pierces its surface with two of his claws. Stretch makes a sound of alarm, but Sans just moans. There’s no intent to hurt in his brother’s actions; it’s just that having access to the inner layers of the soul makes it easier for him to manipulate it. Sans feels his magic taking shape, controlled not by his own will, but by his brother’s.

“Turn around, Sans,” his brother directs, though the words are more for Stretch’s benefit. Sans doesn’t need them. Papyrus is holding his soul. Sans knows exactly what he wants, and so as he turns away he presses his face into the floor, lifting his hips in the air to present his tailbone to his watching audience. He feels another jolt of compulsion, and with a small whine of embarassment he tugs his shorts down to his knees, exposing the naked bone beneath.

“Nice,” Stretch says, and Sans can imagine his leer without even seeing it. He presses his face harder into the carpet.

“Hmph,” Papyrus grunts, not yet appeased. His fingers are curling into the inner walls of Sans’s soul, each stroke a firm demand. Sans inhales shakily, feeling the tight, hot coil of magic gathering in between his legs. It’s always different when his brother forms sexual organs for him than when he forms them for himself. Papyrus demands it to manifest already swollen with arousal, sensitive and dripping with fluids. The fit feels too tight for the relatively narrow cavity of his pelvis, increasing the feeling of pressure within.

This time, the feeling is more unnatural than usual. Sans risks a glance over his shoulder, and beyond the crest of his illium he can make out a new extension protruding from the end of his spine. It’s a tail, short and skeletal, a thin whippet of bone that lashes back and forth in tune with his bewilderment.

“It’s like training a pet,” Papyrus instructs, giving Sans’s soul an approving squeeze. “You need to be firm. Discipline first. And then affection after.”

Now he does smile, looking Sans in the eye. “Good boy.”

His soul is shimmering with pleasure, and the tail starts wagging madly. It’s not controlled by his brother. It’s his own ridiculous, too-eager emotion driving it, and he sinks back in embarrassment as Stretch laughs delightedly at his shameful display.


	7. Underfell Sansby; Aphrodisiacs

**Notes for the Chapter:**

> Content warnings: Underfell Sansby [Underfell Sans/Underfell Grillby], non-consensual drugging that makes for dubious consent even though technically the question is asked, monster heat, food porn, ecto-pussy meets flaming cock (well sort of).

It was the best fucking burger he’d ever had.

Strangely enough, Sans hadn’t even noticed at first. He was already several bites in before his tongue finally registered the pleasant tingling and something warm curled around his soul making him feel better than he had all week. For a moment he was almost perturbed, giving his meal a slow, more tentative taste, but now that he was paying attention he was brilliantly aware of the fact that he somehow had found himself with a mouthful of pure heaven. He groaned softly, taking another frantic bite.

The hamster that usually sat in the corner by the broken jukebox gave him an almost scandalised look. “Geeze, Sans, are you eating that thing or fucking it?”

“Fuck you,” Sans retorted, mouth full and eyes glazed. “This is the best fucking thing I’ve ever tasted.”

The hamster eyed his plate dubiously. It was the same thing Sans always ordered; the cheapest burger on Grillby’s menu. It looked just the same as always, dripping with grease and a too-liberal helping of mustard, but the downright carnal way Sans was swooning over the damn thing must have made for a convincing argument. He sidled up to the bar.

“Hey Grillby, get me one of these, will you?” the hamster called, pointing at Sans’s plate and covertly watching the way the skeleton was practically panting in ecstasy between bites.

Grillby came over, his expression flat. “We’re closing. Come back tomorrow.”

“What!?” the hamster spluttered, a protest that was echoed by the table of dogs by the wall. Grillby didn’t keep precise hours, but usually he stayed open as long as there was money to be made.

“I’ve got shit to do today. Leave.” Grillby’s tone brooked no argument.

The hamster scoffed, shoving his paws into the pockets of his jacket and stalking towards the door. The dogs made a theatrical show of packing up their poker game, grumbling and muttering half-hearted obscenities. When he turns his gaze on Sans, the skeleton gave a distressed whine, clutching his burger possessively.

“You can stay until you’re done,” Grillby told him shortly, and that was enough to ease away any hint of tension.

He should have realised then that something was up, but it was impossible to think of anything but his food as the bar grudgingly cleared until it was just him and Grillby left. Sans was trying not to rush. He wanted every moment with this burger to last forever.

“Holy fuck, Grillbz, what did you put in this thing?” he breathed, awed. Grillby knew his way around a kitchen, sure, and the kind of food he cooked was perfect to slough off the oppressive chill of Snowdin, but this burger was indescribable. The effect was almost euphoric. His soul felt lighter, the near constant weight of his anxiety seeping away with each bite.

He felt relaxed.

Way too relaxed.

He looked up as Grillby came to stand before him, leaning forward on the bar. “I guess you’ve never had food made by a monster in heat before.”

That non-sequitur threw Sans for a second. It took him a moment to realise the implications, and he ended up blinking dumbly at Grillby. “You’re in heat?”

There was probably some sort of joke to be made there, but for once Sans felt his wit fail him. He hadn’t even considered…usually there were tells when a monster was hitting their peak, but upon consideration most of them wouldn’t be obvious on Grillby. How could you notice a fever in the body of a flame elemental? The usual musky scent probably wouldn’t be able to overpower the smell of ash and smoke, if it even manifested on a monster whose body was pretty much made of fire. Most monsters went into hiding until their vulnerable moments passed, but if no one could tell what was going on, he supposed Grillby wouldn’t have any reason to.

Sans took a moment to think about that. Then he stared at his burger with stunned apprehension. “Uh.”

“It acts as a natural aphrodisiac,” Grillby informed him, leaning his chin on a hand. “I had plenty of leftovers prepared for the rest of my customers, but I made that one especially for you.”

Sans was only now coming to some belated realisations about exactly why he was feeling so good. The tingle in his mouth, where the food had interacted directly with his magical taste-buds, was becoming almost uncomfortably sensitive. He was salivating far more than he needed to, and with a small stab of panic he realised couldn’t dispel his tongue because he didn’t want to – it had a mind of its own, and wasn’t ready to lose the taste of the food still lingering in his mouth.

And the feeling in his soul…he hadn’t even recognised it because it had been so long since he’d felt _that_ sort of good. It was pulsing and clenching with excited little beats, making his rib cage feel warm with a heat that was already crawling down his spine.

“I sh-should go,” he stuttered, now very aware of the fact that the bar was empty and Grillby was staring at him intently and, fuck, he could already feel his legs shaking a little and the completely mundane shape of the barstool beneath him was suddenly angled against his tail-bone in a very distracting way.

“You haven’t finished your food,” Grillby pointed out. He’d rolled up his sleeves at some point that evening, Sans noticed, discomfortingly aware of the rare sight of Grillby’s forearms and wrists as he reached out and ran a finger through the congealed juices on Sans’s plate. He held it out to Sans. The liquid bubbled slightly, heating on contact but not burning or evaporating. The smell was heavenly. Sans thought there might be drool leaking down his chin.

“Ah…” He had to say no. He had to go home and take his overdue lashing from Boss about staying out late, and maybe when that was done he could crawl into bed and try and ease out that coil of tension that was starting to build in his pelvis. He was already rocking slightly in place, unable to make himself sit still, and the motion pushed his upper body forward to help balance on the edge of the bar and brough his teeth closer to Grillby’s waiting hand, and-

He couldn’t help himself. He licked the trickle of juice off Grillby’s finger, and that was all it took to open the floodgate and suddenly Sans was lapping at every molten crevices of Grillby’s hand. He’d thought the burger had tasted pretty amazing, but it didn’t hold a candle to the way the elemental himself tasted…though ‘taste’ was probably not the right word. It was the way the magic of Grillby’s body sparked and crackled against Sans’s tongue, electrifying and mind-blowing and _so fucking good_.

“Sans,” Grillby said, and someone who didn’t know the elemental quite so well might have thought he seemed calm, but Sans had known him for years and knew that pretence of control was only barely restraining something infernal. “I would like to fuck you.”

Maybe it was the way he asked, so precise and almost proper. Maybe it was the fact that he’d even asked at all, when he probably could have forced it while Sans was half out of his mind with need. Maybe it was because he’d always kind of liked Grillby. Maybe it was because it had been an unbearably long time since he’d gotten laid.

“Fuck, yes, fine,” Sans blurted recklessly, and practically threw himself over the counter.

* * *

“Fuuuuuuuck,” Sans whined, trying to kick out at Grillby in protest and missing completely. The elemental had him bent over the bar, Sans’s hips balanced precariously on the edge, but aggravatingly this left his feet dangling several inches above the floor. He had no leverage, particularly not with Grillby pinning his wrists up behind his shoulder-blades.

He should have expected that Grillby was going to be a complete piece of shit about this.

“You bastard!” Sans struggled, but only half-heartedly because the hand that wasn’t keeping his wrists maddeningly bound was slowly guiding Grillby’s cock up and down the cleft between his legs. The pussy had formed itself almost entirely without Sans’s consent, dripping and eager, the lips already swollen and sensitive. Grillby’s incessant teasing wasn’t helping in the slightest. “Just-! Augh, stick it in already!”

“It’s so wet,” Grillby said, sounding both fascinated and also kind of appalled. “Why would I want to stick my cock in that?”

Sans snarled in frustration which then rose to a shriek as Grillby let the tip of his member heat until the liquid coating Sans’s conjured genitals began to frizzle under contact. The fact that he still had enough control to prevent himself from searing Sans in any way was unbelievable and absolutely infuriating.

“Then I’ll fucking-hnnnngh! Fucking get rid of it if you stop touching-ah! AH!”

Sans could hardly get a coherent sentence out, spluttering and thrashing against the smooth counter-top to no affect whatsoever. Grillby seemed completely intent on taking his time and working Sans up into a screeching fury of frustration. Sans was starting to think the story about being in heat was complete bullshit. No monster in the throes of their mating cycle should be able to hold back the way Grillby was doing.

“No need,” Grillby mused, thrusting shallowly between Sans’s legs, making the skeleton arch with a yelp at the very fleeting contact against his clitoris. “I’m sure I can think of other ways for you to satisfy me. Besides, I’m enjoying listening to you scream.”

Sans shuddered, eyes clenching shut. He should never have agreed to stay.


	8. Toriel/Asgore/Sans; seduction and size-kink

**Notes for the Chapter:**

> Warnings: Toriel/Asgore/Sans, consensual fluffy build-up with Boss Monsters seducing a vry smol skel. Toriel totally tops them both.

Sans was used to being looked down on, both figuratively and literally. Neither of these tended to bother him, usually. He preferred it when people didn’t expect too much from him, when his presence was practically a negligible factor. It was reassuring to know that, hey, nothing he did really mattered and _he_ didn’t really matter and so then if nothing at all really mattered then that was  just how things were. He tried to think of it as a very low-stress way to live rather than the painfully depressing burden it often felt like.

And as for being physically looked down on…well, he kind of enjoyed that too, but in quite a different way. He liked that Papyrus would sometimes pick him up and carry him around apropos of nothing. He liked that even on Grillby’s tallest barstool he still had to lean back if he wanted to watch the subtle tells of Grillby’s expression every time he told an awful fire-related joke. He definitely enjoyed the first time Toriel leaned down to hug him and his face ended up buried in her cleavage, warm and soft and even though the position was really only an innocent consequence of his height, he couldn’t help feeling incredibly guilty.

Especially when her ex-husband had been watching.

But Asgore was not at all possessive or territorial of Toriel. Sans wasn’t sure if time had healed over that particular wound or if perhaps they’d always been permissive of each other’s personal freedom. He was starting to suspect it was the latter, because Sans had a good eye for reading people. He could tell from the looks Asgore directed at Toriel that he still loved her. That he still wanted her. That he would work for centuries if it meant earning her forgiveness. The home he had made for Frisk, though the human only lived there part of the time whilst the rest was spent with ‘Mom’, went a long way towards rebuilding their broken relationship, and for a while Sans had been pretty sure he would have to gently mould his own feelings from untried infatuation into a deep but otherwise platonic affection.

Except that he was now almost positive that Asgore was trying to set him up with Toriel.

It might have had something to do with the way the King had, with great care and dignity, scooped Sans up and deposited him into Toriel’s waiting lap at her mild request.

“Uh,” Sans said, profoundly.

Asgore gave a benevolent smile, not at all perturbed by the critical failure of Sans’s vocabulary.  

Toriel giggled, but it was a sound of delight rather than mockery. “He is adorable, is he not?”

“I’m not sure he would appreciate the same sentiment from myself,” Asgore replied, but the way he beamed at Sans betrayed his own amusement.

Sans refused to be flustered, and thought he was mostly succeeding. He shrugged casually, as if he sat on the thighs of beautiful women all the time. “I dunno. I could _goat_ used to it.”

The pun was mostly for Toriel’s benefit, and she laughed just as richly as he hoped, but Asgore chuckled as well and Sans felt a slight flush of not-wholly-concealed gratification. He was starting to wonder if it wasn’t just _Toriel_ Asgore was looking to set him up with. They were quite an intimidating team when working in tandem.

Asgore leaned in closer, and Sans was intensely aware of the way Toriel’s hands had come to rest on the sides of his rib-cage. She could practically engulf his chest in her grip, but her strength was  masterfully controlled. There was nothing especially untoward in her touch, but Sans had always been able to sense a little more than the average monster and he had to work at not being overwhelmed. Even a single Boss monster was already a bit much to take. Their presences were so powerful, and they radiated everything that made up the essence of all monsters. Compassion. Hope.

_Love._

“You’re trembling,” Toriel murmured, but even though she was right, Sans found it impossible to feel shame. The sheer empathy he could feel pouring from her soul wouldn’t let him.

“Yeah, uh…” Words were becoming difficult again. He almost wished Asgore would look at him with resentment or disgust, but there was nothing in his gaze but sincere understanding and something wistful he’d often mistakenly assumed was meant entirely for Toriel. “I was…I was thinking…”

“How troublesome,” Toriel said, and though Sans couldn’t muster the courage for it, she had no reservations about dragging Asgore forward by the impressively gilded mantle of his cloak. “Perhaps you shouldn’t?”

Her muzzle was nestled against one side of Sans’s neck. Asgore mirrored her on the other side with very little prompting. Sans was surrounded by warm breath and silky fur and rising heat and potent magic and he felt so small compared to either of them, and yet also entirely safe.

“Okay,” Sans agreed, his mind already in the process of shutting down in a fashion that felt entirely too agreeable. A second set of paws took up occupancy on his hips. His legs were coaxed further apart as Toriel adjusted him on her lap. “Oh boy.”


	9. Underfell; gen hurt/comfort

**Notes for the Chapter:**

> Warnings: Graphic description of violence and broken bones. A rare gen-fic amidst the rest of the trash.

Papyrus is dropped off on their doorstep in pieces.

“Delivery from the Captain,” the guard says, his expression hidden by his armour and voice flat enough that Sans can’t read him at all. He doesn’t appreciate the way the guard carelessly dumps his brother’s body into his arms, but he’s a little too distracted to give the monster a proper piece of his mind.

“Nyeh heh heh,” Papyrus gasps, and the fact that he’s still conscious is both amazing and horrific in its own right. Despite his wounds, there’s an unholy note of glee in his rasping voice. “I almost beat her this time, brother.”

Sans stumbles under his weight, dragging him into the safety of their home and kicking the door shut against the possibility of prying eyes.

“You’re an idiot,” Sans hisses, impotently furious, because Papyrus won’t listen to him (not that he ever has, much) and hasn’t given up on his crusade to convince Undyne to let him into the Royal Guard even though each time he comes back it’s with more scars and fractures. Next time his brother might very well be returned to him as a jar of dust, assuming Undyne doesn’t just use the ashes to salt her garden against weeds.

Papyrus is only barely coherent, so Sans takes the risk of using a shortcut to get them back to his room since trying to haul his brother up the stairs would be hell on both of them. Papyrus doesn’t even seem to notice the shift, head lolling weakly on Sans’s shoulder as the smaller skeleton strains to lay him out on the mattress. Papyrus will probably bitch about the state of Sans’s room later, but he doesn’t kid himself into thinking he’s strong enough to lift Papyrus onto his own bed, which actually has a proper frame, without doing more damage to his brother’s crumbling bones.

“Fuck,” he says, reviewing the damage and trying not to quake. There’s so many breaks. His body is staying together, but only from the same magic that keeps a skeleton assembled in the first place. It’s holding all the bones roughly where they need to be, but the strain of juggling all the pieces will be haemorrhaging Papyrus’s strength until he can release them.

Sans will need splints, and a hell of a lot of bandages.

The splints are easy. He can conjure his own magic into thin bones in all the right shapes to match his brother’s fractured limbs. For bandages he tears into his crumpled ball of sheets because he can’t remember if they have any, and if they did, only Papyrus would know where to find them. He can’t ask. Papyrus is only on the very edge of consciousness, huffing with pain. If he passes out, his bones will fall to bits and Sans will have a much harder time putting him back together.

“Bet she’s surprised she didn’t dust you,” Sans says, because he heard once that talking to someone helps to keep them awake. Tempting as it is to chastise his brother further for being a suicidal fucking moron, he suspects Papyrus might spitefully lose consciousness just so he wouldn’t have to listen, so Sans tries a different tactic; saying what he’s sure his brother will want to hear. “She must be pretty damn impressed. She even sent someone to make sure you got back here okay, so you must have gotten into her good books, yeah?”

There might even be some truth to that. After all, if Undyne wants Papyrus dead, she can just kick his broken body over a waterfall. She doesn’t need to send someone to deliver him home where he can rest, recuperate and possibly come back to try again.

Then again, maybe she doesn’t think even Papyrus is that insane.

“I bet she’ll be making you an offer any day now,” Sans goes on, working as quickly as he can manage. He has to keep his hands steady. He has to not think too hard about what he’s doing or he might be tempted to throw up. These are both important life skills he learned in the Labs, and they’re serving him well now. “She’s probably just testing your strength so she knows how high up the chain you need to be. I heard from one of the dogs she never got around to replacing her second in command, and the King told her to fix that, so…”

He babbles on, trying not to let his voice waver every time pieces of bone grind together, flaking dust into the crevices of his mattress. He flinches in sympathy every time his brother’s voice gurgles in pain, but Papyrus is remarkably tolerant of his fumbling. He’s still and mostly silent, letting Sans manhandle him with a lack of complaint that’s almost eerie. Usually his brother has a lot to say, mostly unfavourable, about anything Sans does. Sans would readily dismiss his lack of response as the consequence of agonised fatigue, but when he finally looks up he realises Papyrus has become more alert and is watching him silently. The lights in his sockets are dimmer than usual, but steady and focused.

Sans promptly loses the thread of his inane rambling and shuts his mouth with an audible click. Unfortunately that begins a chain reaction, rekindling his awareness of the surroundings and his own body, and now that he’s paying attention he can feel the slick coagulation of marrow on his hands and the faint strain of his own magic holding onto the bones that are keeping his brother’s pieces together.

And the deep-seated knowledge of what could have been twists into him like a knife. He makes a choked noise and has to look away, eyes stinging with emotion he’s no longer used to expressing. Papyrus wouldn’t thank him for the sentiment.

“You’re still an idiot,” he says gruffly, when he thinks his voice is reliable enough not to crack on the words.

Papyrus doesn’t retort, but his mangled hand finds its way to Sans’s wrist, squeezing lightly.


	10. Underswap/Underfell Foursome

**Notes for the Chapter:**

> Content Warning: Foursome [Underswap Sans/Underswap Papyrus/Underfell Sans/Underfell Papyrus], bondage, teasing, ecto-parts.

“Bro,” Papyrus croaked, sounding positively tortured. “Can you at least take the blindfold off?”

“No! Mweh heh heh!” Blue almost felt guilty, taking such enjoyment in his brother’s pain, but not enough to comply with the request. He parted his femurs a little more, letting out a sigh of contentment as Red pushed further between them, lapping noisily at the conjured cock between his legs. “Ahh, Red. You’re doing such a good job!”

Red made an appreciative sound, exaggerating it for Papyrus’s benefit. He looked good, kneeling at Blue’s feet wearing nothing but his collar. His expression was uncharacteristically relaxed as he worked, his tongue skilfully teasing Blue’s shaft from base to tip until Blue was forced to ease him back with a gentle tap to the skull. He didn’t want the fun to end too soon. Red complied obediently, seeming perfectly content to simply be following Blue’s directions. It made him an excellent partner in crime.

“Now then,” he said, turning to their brother’s. “Which of you deserves a reward, hm?”

His own Papyrus groaned, while Red’s brother let out a furious gurgle of protest behind his gag. Blue sniffed haughtily in his direction. “I don’t know what you tried to say, but I bet it was rude! So no reward for you. Red, go give my brother a kiss.”

“Oh thank fuuaaaah-fruitcake,” Papyrus finished awkwardly, remembering at the last second that swearing was liable to be punished with gagging. Blue decided to let it slide this time, watching appreciatively as Red crawled over to the taller skeleton and climbed eagerly into his lap. Red straddled Papyrus’s hips and just let himself rest there for a moment, letting Blue enjoy the way his brother’s hips tried to rock and buck for any friction against the stifled bulge between his legs. Red deftly avoided it, leaning over and clinking his teeth against Papyrus’s collarbone with a smirk. Well, Blue hadn’t specified exactly _where_ to give that kiss. It was nice that Red seemed to be on the same page as himself.

Papyrus squirmed in his bonds, earning another outraged, muffled snarl from his fellow captive since the struggling make the ropes chafe where their elbows were bound together. Blue had both Papyruses bound, back to back, their arms crossed and fastened to the framework of their seats so that they couldn’t help but feel each other with each tug of movement. Blue’s brother had only put up a half-hearted struggle against his capture, pretending to let himself be distracted by a lapful of Red whilst Blue had tied the knots. Only after he was finished and  Papyrus had tentatively tested the bonds did he start to look nervous. Apparently he hadn’t realised how much Blue had improved under Alphys’ training.

Red’s brother, Boss, had been another matter entirely. It had taken both Sanses to hold him down, Red pinning him by the soul and using all his strength to lock his arms in place while Blue struggled with the ropes. It had been quite a session of vigorous exercise, with Red panting and cursing from the exertion and Boss swearing obscenities at both of them until Blue had fastened the gag. It hadn’t escaped his notice though, that Boss hadn’t fought back with magic, or even with all of his strength. Blue was more robust than Red, but he still struggled with the handicap of having only 1HP. Boss had been careful with both of them, even if it meant an embarrassing defeat.

Blue came to stand in front of him now, unfaltering in the face of Boss’s silent glower. His femurs had been bound to his shin bones, preventing him from unfolding his legs and forcing them to stay elevated and awkwardly spread on the edge of his chair. It left Blue with an unobscured view of the magic coalescing in Boss’s own dark trousers, and as Blue admired the faint glow of magic with unabashed interest, the flush of colour on Boss’s cheekbones grew brighter. Eventually he turned his head away, unable to stay composed under Blue’s gaze, making the smaller skeleton laugh fondly.

“No need to be shy,” he said, kneeling down between Boss’s legs and placing a hand over the swell of magic. Boss grunted, jolting hard enough to make Papyrus yelp at his back. “You tie Red up all the time. You’re allowed to like it too.”

Boss huffed a negative, yanking futilely at his restraints. Blue’s expression shifted from gentle encouragement to devious amusement. He held up a hand, letting a sharpened bone construct form in his palm. Boss stared at it with trepidation but not with fear. That was good. It had taken some time for him to trust fully that neither Blue nor Papyrus would do any harm, overriding his natural instinct to expect it.

“You just need to relax more,” Blue advised him brightly, hooking the end of the bone into the fabric of Boss’s pants and gleefully sawing it open. That earned him a more aggrieved splutter of sound, but Blue ignored it. Boss had plenty of spares. More important was the way his eyelights dilated as he watched the careful movement of Blue’s construct, his body suddenly going very still as it tore away the protection of his clothing and bared his pelvis to the air. His magic hadn’t fully formed yet, but the thick, red haze suggested it wasn’t far off. “Let me help you with that!”

Blue leaned down, letting his tongue unfold slowly from between his teeth, holding Boss’s eye as he let it graze deliberately over his pubic bone. Boss shuddered, the gentleness more effective than rough abrasion would have been. With a reluctant groan, his magic took the soft shape of a vulva, the lips of the labia already swollen with need. Blue beamed, delighted.

“How pretty,” he cooed, making Boss blush further, but he didn’t struggle as Blue lifted his legs to gain better access for his mouth to explore this rare manifestation of Boss’s magic.


	11. EdgeBerry; Daddy-Kink

**Notes for the Chapter:**

> Content Warning: Edgeberry [Underswap Sans/Underfell Papyrus], assumed daddy!Gaster for both, parent roleplay, Blue is a kinky little thing.

“Hold still!” Blue directed, approaching Papyrus’s skull with what looked suspiciously like a marker. Gritting his teeth, he patiently endured as the smaller skeleton leaned close, his face furrowed in concentration, and began delicately tracing a line upwards from the tip of Papyrus’s scar to the top of his skull. He traced a similar line down from the edge of his left eye-socket as well, ending it at the chin.

Blue leaned back to admire his handiwork, and clapped his hands together. “Perfect! Have a look!”

He brandished a mirror, and Papyrus almost jolted at his own reflection. He hadn’t really thought he looked all that much like Gaster, but dressed up in a labcoat and with a few false cracks added the resemblance was jarring. The only telling imperfection was that his own scar ended slightly below the right eye as well, but beyond that, the embellishments were surprisingly convincing.

He made a note to ensure all the marker was scrubbed off before his own Sans saw it. As difficult as their relationship could sometimes be, he didn’t want to give Red an unexpected heart-attack over a case of mistaken identity.

“Put these on too,” Blue insisted, his eyelights a dilated, sparkling blue that Papyrus had no defence against. He allowed Blue to push the glasses onto his face, adjusting them until they balanced precariously on his nasal bone. Thankfully the lenses were glass, so they didn’t impair his vision. He wondered where Blue had found such a thing. It suggested a level of preparation that defied the supposedly spontaneous request for something a little more ‘interesting’ in their usual play.

Dubious as he was, it was hard to argue with the effect it had on Blue, who looked positively star-struck. “W-wow. You look…so respectable!”

Papyrus growled. “I _always_ look respectable.”

“But not science-y respectable!” Blue said, with a dramatic pose to try convey more legitimacy to the idea of 'science-y respectable’ which Papyrus was fairly sure was not actually a thing.

He was about to argue this very point when Blue abruptly vaulted up to straddle his lap, derailing his train of thought as a pair of arms wound around his neck.

“Hey Daddy,” Blue murmured with quite a respectable purr, lowering his voice in a way that went straight to Papyrus’s marrow, heat flaring in his bones.

“I prefer 'Doctor’, Sans,” he corrected, trying to modulate his own voice to the haughty, staccato tones he vaguely recalls his father using. He assumes it’s the same for Blue’s memory of him, though he’s not entirely sure. Reliable information on Gaster is difficult to find, no matter which universe it is. “Or 'sir’.”

“S-sorry, sir,” Blue replies meekly, his pupils expanding even more. The slight stutter wasn’t from fear, real or feigned. It was because he was suddenly salivating intensely, his mouth dripping wet and inviting in the way Papyrus has come to know all too well. He looks up coyly into Papyrus’s face, one hand trailing down his chest. “I know you have important work to do, but I thought we could…spend some time together?”

The teasing hand came to rest on Papyrus’s crotch, making his hips twitch unintentionally. He let out a hiss, one hand coming up to hold the glasses in place since his movement nearly sent them askew. “I…have very important experiments, Sans. Delicate, sensitive experiments…”

“I can help,” Sans breathed, sinking down onto the floor between Papyrus’s knees. He pulled off his gloves, revealing surprisingly elegant phalanges beneath. His expression was one of assertive enthusiasm. “I have very steady hands. Let me show you.”


	12. PapyrusxSansxGrillby

**Notes for the Chapter:**

> Content Warning: Post-Pacifist Papyrus/Sans/Grillby, domestic relationship fluff that becomes covert public sexytimes.

Grillby doesn’t ‘go out’. It is just not a thing he does. His life revolves around his bar, especially now that he’s had to re-establish himself on the surface. There’s no end to the amount of cooking, serving, cleaning, sorting, and mixing he has to do, even with the addition of his new skeletal assistants. Well, Papyrus assists. Sans mostly sits at the bar and chats with the customers, but he’s good at amusing the humans and keeping tensions low between the two races so in his own way he is providing a valuable service.

Even so, Grillby is far too busy for frivolous outings. His employees apparently disagree.

“YOU HAVEN’T HAD A DAY OFF IN THREE MONTHS,” Papyrus reminds him, his grip on Grillby’s arm unyielding as he drags the elemental down the street. Grillby looks mournfully over his shoulder at the door to the bar which is swiftly disappearing into the distance. “EVEN I, THE GREAT PAPYRUS, UNDERSTANDS THE IMPORTANCE OF REGULAR PERIODS OF RESPITE.”

“Besides, what’s the point of living in a human city if you don’t get out to see the sights?” Sans says, grinning up at him. Somehow his meandering pace manages to keep up with Papyrus’s long, determined strides, though that may be because Grillby’s unenthusiastic accompaniment is acting as a bit of a lodestone. “So let us take you on the tour. Pap’s practically an expert on human hot-spots. I’m sure you’ll like them.”

Papyrus preens for a moment before realising the pun and blustering in offence. Grillby soothingly pats his arm, finding comfort in the familiar act of standing between them, literally and figuratively, to mediate their sibling bickering.

At Papyrus’s insistence, they make their way into a bustling club that’s practically vibrating with too-loud music. The rhythm is familiar, and he’s not entirely surprised to see the decor is themed in Mettaton’s distinctive style. The place seems to be an affiliate of the MTT resort, which explains the monster-friendly door policy.

Grillby would have raised an objection if he’d thought it would have done any good. The problem with dark interiors is that he unavoidably stands out, and very often ruins the intended ambience. His own innate light also tends to draw the eye, particularly of humans, and then when they realise what they’re looking at, they stare.

It’s…uncomfortable.

“THIS IS ONE OF MY FAVOURITE PLACES,” Papyrus tells him earnestly, somehow still making himself audible over the music as he drags Grillby into the mass of writhing bodies. People immediately give them space, but that may be because they expect to get burned by the small wisps of flame Grillby gives off, as if his control were so poor as to allow that. Papyrus is unafraid, however, and wraps both arms around Grillby’s neck, leaning intently against him. “DANCE WITH ME?”

He can’t bring himself to say no, even if he doesn’t really share Papyrus’s appreciation of the place. He gets enough of noise and bustle in the bar. In what little downtime he used to have, back in Snowdin, he preferred to spend it in quiet and solitude, with slower, calming music and occasionally a good book. Reflecting on that, he starts to wonder if his habits are turning him into an old man before his time.

The club suits Papyrus perfectly, however. The younger skeleton dances unabashedly and with full enthusiam, though he never strays far from Grillby’s arms. This type of dance apparently requires a lot of touching and pawing, and Grillby can’t deny there’s some enjoyment in letting his fingers grace over the sleek ivory of his partner’s bones. Papyrus is wearing very little; only a pair of incredibly short shorts, and a crop top with 'PARTY SKELETON’ emblazoned in a sparkling script (the original word 'GIRL’ has been crossed off with marker to make room for the amendment). There’s a lot of him that’s free to touch, and if Grillby focuses just on that, he can nearly ignore the rest.

Nearly. It still tires him far too quickly. He glances around and catches sight of Sans at a table on the edge of the dance floor, having taken the much more sensible approach of watching them instead of participating. Grillby gestures to Papyrus, pointing in Sans’s direction and signing his need for a break. His voice isn’t loud at the best of times. There’s no way he’ll be able to make himself heard in here.

Papyrus isn’t very good with signing yet, but he understands enough to take the hint. “OF COURSE! LET US GO KEEP MY BROTHER COMPANY.”

At some point during the dance, Grillby’s tie has somehow disappeared into Papyrus’s pocket, and the first three buttons on his shirt have been popped loose. He doesn’t bother to correct it, letting Papyrus take him by the hand and lead him over to Sans’s table. The smaller skeleton’s grin turns deliberately lascivious as they approach. “Lookin’ good, Grillbz.”

“HE IS A MUCH BETTER DANCE PARTNER THAN YOU, BROTHER,” Papyrus sniffs, but there is still a barely repressed radiance of pleasure about him. Grillby doubts the club is Sans’s sort of place either, but if coming means seeing Papyrus with such an unadulterated expression of joy on his face, he can understand making the effort.

“Sorry, bro,” Sans says, sounding unapologetic as he shuffles over to make room for them on the bench. “I just don’t feel it in my bones the way you do.”

“AUGH. SANS!”

Once again, Grillby takes the space between them, and Sans immediately nestles against his side. He looks less tired than usual today, his eyelights bright as stars in the depths of his sockets. Despite his discomfort, Grillby can’t entirely regret being made to come with them.

Sans nudges a glass in front of him. “I got drinks. Dancing is thirsty work, y'know.”

Papyrus is given a tall, colourful glass full of frothy layers which Grillby suspects contains more decorative paper umbrellas than shots of alcohol. Grillby gets a glass full of whisky, no ice, which he takes appreciatively, giving Sans a smile. The first sip ignites on his lips and burns pleasantly in his mouth. He feels sharper, immediately more alert, and suddenly the exuberant energy of the club doesn’t seem so overbearing.

“I made it a triple,” Sans murmurs against him. “Thought it might help.”

Grillby nods, taking a longer draught and feelin the way his flames roil and brighten. He doesn’t get overheated, naturally, but he takes a moment to roll up his sleeves to let the magic of his body blaze more freely. Sans seems to approve, judging from the way he discreetly grazes a finger down the length of Grillby’s forearm. He’s almost starting to think he might be game enough to brave the dance floor with Papyrus again when the other skeleton suddenly stands up excitedly in his seat.

“OH LOOK! MY HUMAN FRIENDS ARE HERE TONIGHT! HUMANS! HELLO!”

Papyrus waves enthusiastically to a small group of humans, and Sans nudges Grillby to get his attention. “Pap’ll help you get acquainted. If they ask, I’ve gone to get drinks.”

And then he disappears, leaving Grillby to blink oddly at his empty seat. Papyrus doesn’t seem to notice. He’s too busy greeting his gaggle of friends, most of whom seem to be part of the young, trendy crowd who have been very vocal about their acceptance of monsters. They return Papyrus’s greeting sincerely, and Grillby wonders if Sans has some sort of a problem with them, to have left so abruptly.

Then he feels a small, skeletal hand on his knee, and realises Sans hasn’t left after all.

“So Papyrus, is this the 'hot boyfriend’ Sans was telling us about?” one of the humans asks, beaming at Grillby. Thankfully Grillby’s face doesn’t have a very solid form, making it particularly difficult to read. Apparently the human can’t tell he’s busy processing the fact that Sans is nibbling his way along Grillby’s thighs, pushing his legs further apart as he works his way towards the elemental’s groin.

“YES! THIS IS GRILLBY! AS SANS WOULD SAY, WE ARE…BONE-FRIENDS? NYEH HEH HEH.”

The humans apparently enjoy a decent skeleton pun, which is good because Grillby hasn’t yet found his tongue and is just doing his best to sit as still as possible while Sans cheerfully molests him beneath the table. Thankfully the humans aren’t at any sort of angle where they’d be able to see. Papyrus presses against him, looking at Grillby with an earnest, hopeful expression, his cheekbones flushed with orange and–

Oh, he definitely knows what Sans is doing. Grillby wonders if the brothers planned this, or if they just anticipated each other well enough to act so seamlessly in tandem.

“That’s adorable,” another human gushes. “Can I take a picture?”

“YES!” Papyrus exclaims even though Grillby is gripping his arm with silent but meaningful force. “MAKE SURE YOU SEND IT TO ME LATER! I WANT TO COMMEMORATE THIS EVENING IN MY MEMORY. THIS IS THE FIRST NIGHT I HAVE CONVINCED GRILLBY TO GET OFF IN THREE MONTHS.”

He’s pretty sure he hears Sans choking of laughter from somewhere down near his lap. Grillby refuses to plant his face into the surface of the table no matter how appealing the action suddenly seems.


	13. US!Papyrus/UF!Papyrus; helplessness

**Notes for the Chapter:**

> Content Warning: SpicyHoney [Underswap Papyrus/Underfell Papyrus], bondage, blindfolds, gagging, humiliation. Might be dub-con, or else Swap!Pap is an incredible sweet-talker to have convinced Fell!Pap to go along with this.

Struggling against ropes is a surprisingly exhausting activity. He’s never had doubts about his own stamina, but even though he can’t tell the passing of time very easily behind his blindfold, it feels like a disgracefully short length of time before he’s subdued to breathless, restless panting. All of his joints ache with the strain of his furious fighting, so now the tension of his bonds is twice as uncomfortable.

He hears the small hiss of a match being struck, and a moment later the smell of fresh cigarette smoke invades his nasal cavity. He grunts his irritation, wishing for the opportunity to berate his counterpart for the disgusting habit, but his jaw has been quite firmly taped shut. The Great and Terrible Papyrus, silenced by ordinary household duct-tape. The humiliation won’t be quick to fade.

“Are you done?” the other Papyrus asks, lazily unconcerned.

The comment sparks another furious minute of twisting and writhing, but his energy fades more quickly this time. Exertion has worked up a fine layer of sweat over his bones – definitely the result of effort and not nerves! – and he’s feeling increasingly uncomfortable with the slick, filmy layer of his own secretions. Disgusting. He’ll need a shower after this.

“Well,” the other Papyrus muses. “Took you a while to wear yourself out, huh?”

A hand is placed suddenly on his chest, and he bucks once, trying and failing to throw it off. He snarls something foul behind the gag, but the muffled screech of his voice isn’t any more effective than his movement had been in dislodging the unwelcome touch. It starts to trace idle circles over his breastplate in casual exploration.

“You know, I have to wonder about this outfit of yours,” he counterpart says, fingers creeping lower. Papyrus is braced for it, but he still flinches when bony fingers wrap around the exposed column of his spine. “Seems a bit of an oversight that you have all this bone on display. Kind of shameless, isn’t it? Wouldn’t it make more sense to keep it hidden under armour?”

Obviously he had some extremely sensible reasons for that. Armour was encumbering, particularly for a skeleton who lacked the padding of muscle and fat to bear the weight of heavy metal. Steel on bone was noisy too, and would have denied him the valuable stealth needed to launch an ambush. He preferred just enough to keep his ribcage protected, to deflect any blow aimed at his soul if needed, but he preferred to stay flexible and light on his feet. Of course he wouldn’t stupidly burden himself with unnecessary layers.

“You know, whenever I stand next to you, I can see right down into your pelvis,” Pap continued, his breath whistling slightly on the exhale as he breathed out smoke. His hand dropped to Papyrus’s belt, tugging at the buckle. “What are you, some kind of exhibitionist?”

He snarls in aggravation, because even though he hadn’t thought he had any modesty to speak of – his Universe doesn’t make a big fuss out of such things – he still somehow feels flustered by the comment. Shameful. Worse, his hips try to jerk away from the intrusive, grasping hand but the awkward angles of his prone position causes him to inadvertently press up against it. There’s a brief, tantalising pressure across his groin that sends an electrifying jolt right through him. It’s positively infuriating.

“Whoa. Eager all of a sudden, aren’t you, kitten?”

The pet names are even more mortifying. He tries to shriek his indignation, making an impressive amount of noise behind the tape and thrashing . Pap simply leaves his hand resting against the crotch of his pants, and each arch of his spine ruts his pelvic mound against the slack weight of his knuckles. Pap isn’t even working to stimulate him. Papyrus is making all the effort himself, and it’s downright degrading that after the initial fury passes he can’t stop his hips from rocking up against the pressure, trying to encourage more contact.


	14. Gaster/Sans; tentacles

**Notes for the Chapter:**

> Content Warning: Sanster [Sans/Gaster], non-con, because crazed void creatures don’t even know the meaning of consent. Goop and tentacles, possessive molesting, sensory deprivation, extreme penetration, author has no idea what to make of any of this.

“Come on, G,” Sans drawled, staring blankly into the nothingness around him. “Don’t leave me _hanging_ here.”

His arms were submerged up the the elbows in something cold, thick and clinging. They were pulled roughly over his head, though it was difficult to ascertain if he was really being suspended in any way. Gravity was a tenuous sort of concept in the void. There was no real up, down or sideways. It somewhat detracted from the effect of the pun, but that wasn’t really the point. It wasn’t for humour, or even really for Gaster’s benefit since Sans wasn’t entirely convinced his former mentor could really comprehend anything he said.

The words were for himself, as a reminder that he still existed here in the Void where nothing else did – or rather, where nothing else _should_.

Something brushed against his knee. Sans closed his eyes, swallowing tightly. It didn’t make any difference, whether they were open or not. He couldn’t see anything, but he could sense Gaster’s presence in the non-air, like feeling ripples through water of something enormous circling unseen around him. It would be terrifying if familiarity hadn’t sapped his helplessness to a broken sense of apathy. He’d been here too many times before, and nothing he could do would change the outcome. Poor jokes and morbid humour were his last refuges.

 _ **Saaaaaaaans**_ , Gaster hissed in a voice without sound. It was still strange, hearing him in a way that didn’t involve watching his hands move even if technically it was still voiceless. He didn’t think there was even the right words in any language to describe the way Gaster communicated now, but if pushed he’d have likened it like hearing static inside his head, jarring and wrong and impossible to tune out.

“Yeah, yeah,” Sans grumbled wearily, going even more limp against the hold on his arms. “Just get on with it.”

Gaster’s voiced burbled incoherently with distorted iterations of Sans’s name. Sans knew better than to assume it was any sort of direct response. There was a lot of uncertainty involved, since despite how many times he’d been here there was no way to be sure of anything. Could sound carry through the void? Did Gaster even still posses ears to hear with? Was he still sane enough to comprehend? Did he even care? Any one of those questions could easily be answered with a no. Sans’s efforts were only perfunctory these days.

A tendril of darkness curled around his knee. Sans flinched a little, and convinced himself it was just a reaction to its frigid temperature. The darkness was always cold, or rather, completely absent of warmth. The contrast made the touch all the more acute. He could feel the way it wound uncomfortably around his joints, looping between the head of his fibula and his tibia, engulfing the patella, clinging greedily to his femur. It pulled, making his leg joint flex in its socket, stretching out his spine and putting pressure on his arms. Sans bore with it with only a short stutter of his breath.

More tendrils were closing in, latching on to his body with a hunger that used to terrify him. Slender, sinuous tentacles pushed in between his ribs and wove through the bones in a smothering net. Another coiled around his neck, wrapping around tight and thick, like a brace. Even though he was trying his hardest not to fight since it would only be wasting his own energy, the tightening restriction made Sans quiver out of reflex, especially when he felt something longer and thicker probing around near his tail bone. It seemed to take a moment to map out the circumference of his pelvic inlet, considering it in an almost intelligent fashion.

Sans braced himself. It didn’t help. The jolt of the tendril crudely forcing its way through his pelvis still jarred his entire body, loosing a gasp of pain that was immediately swallowed by the Void.

 _ **Saaaaaans**_ , Gaster whispered again, and the noise was worse this time, splitting through Sans’s skull like the discordant screech of nails on chalkboard. There was a garble of feeling beneath it, something like _wantneedtouchtakeposessMINE_. Something that keened in desperate relief as the wriggling appendage shoved further inside him one aching inch at a time, dragging itself up his spine until the tip was lapping at his lower-most ribs.

Sans shook through the nearly unbearable penetration, feeling what little give his bones possessed trying to accommodate the thick intrusion. He almost wished it would go too far and too fast and break him already, because that tended to jolt him out of this nothing space and back into waking reality, but Gaster had learned just enough to be careful, prolonging the torment and Sans’s stay as much as possible.

It might not have been wholly intentional. Sans was pretty sure he was the only one unlucky enough to end up here – some sort of karmic retribution for having stared too long into the Void – and aside from his unplanned, involuntary visits, Gaster was completely alone. Alone in a nothing space, both infinite and empty. Sans tried not to imagine it. The horror was unthinkable.

So Gaster, or whatever was left of him, tended to get very…excited, by his presence. There was an unholy sort of ecstasy in Gaster’s screeching as he wrapped Sans in his formless body, desperately thrusting against him and through him as if trying to meld their bodies together, tying himself to something familiar and stable with a maddened, mindless need.

The first few times, Sans had cried; from sorrow and guilt and pity and fury, but it was hard to hold on to any of that. Hard to stay angry when he was probably the only relief Gaster had from unbearable isolation. Hard to feel compassionate when Gaster recklessly violated every crevice of his body, crushing and defiling and cruel in his complete lack of real comprehension of what he was doing to Sans.

Something shifted. It might have been his body, or possibly the void itself. Either way, the angle of the fearsome appendage inside him altered slightly, and now each time it pushed its plump body scoured over his coccyx in a new, breath-taking way, and Sans coughed out a wretched sound. He could nearly convince himself these days that he didn’t care. That what happened in the void was like a nightmare; unpleasant but largely inconsequential. He could take refuge in numbness, almost, except when the sensation started to build in confusing cacophony of pleasure along with the pain. Giving in meant he had very little defence against it, and so it was somehow especially brutal when the monstrous rippling of the tendrils began to soften and squeeze in gentler but equally devastating ways.

“Ha! F-fuck. Gaster, wait-!”

But Gaster still couldn’t hear him, or maybe still didn’t care. The tentacle thrust in, now starting to fill up his chest cavity, and Sans could do nothing, helplessly skewered on its length as he began to shudder towards his peak.


	15. Papyrus/Grillby; fluff

**Notes for the Chapter:**

> Content Warnings: Papyrus/Grillby vibes, but mostly pre-relationship ruminations. Grillby ponders the puzzle of the skeleton brothers. Papyrus drinks a milkshake. Sans sleeps through everything. Fluff factor turned up to maximum.

Sans was sleeping at the bar again.

It wasn’t on its own a usual sight. Sans was known to have the occasional off day, but this was the fifth night in a row. It was taking all of Grillby’s impressive self-restraint not to say something every time Sans came in, hollow-eyed and smile lilting. No amount of asking would get Sans to say anything if he didn’t want to, anyway. Others had tried, and Grillby had watched Sans cheerfully deflect, joke, and occasionally outright vanish in the face of persistent enquiries into his health. Whatever he was dealing with, he seemed particularly determined to shoulder it alone.

The door burst open with an overly enthusiastic push that was then hastily corrected as the perpetrator apologetically closed it against the forceful gust of the evening breeze that eagerly dashed in. Grillby felt his skin flicker with the sudden burst of fresh air, and wasn’t at all surprised to see Papyrus, who paused and carefully extracting the tail of his scarf from the door-jamb with a grumble.

The tall skeleton paused to survey the room the way one might scour the landscape for threats, but when he found it empty save for Grillby and Sans, some of the tension in the set of his shoulders drained. Grillby hadn’t thought too hard about the reasons – he wasn’t one to judge – but he’d noticed Papyrus was never all that comfortable around the other patrons, or around people in general. It seemed entirely at odds with his brashly assertive personality and purported desire for popularity. Some of the townsfolk mused over this, and called it bizarre. Grillby had just accepted that was the way Papyrus was.

“Hello, Papyrus,” he greeted as the skeleton approached. It was only when the bar was practically empty that his soft voice could carry at all.

Papyrus offered a long-suffering sigh. “Grillby. I apologise once again for my brother. I am sure he doesn’t mean to keep you from closing.”

“I don’t mind,” he replied, and he really didn’t. There was nothing at home to keep him aside from the usual evening routine of dinner and tidying up his largely neglected apartment. Lingering in the bar was at least an excuse to begin his morning prep work and, even asleep, Sans was good company. He demanded nothing, and offered only the soothing sound of deep breathing.

The dark shadows under Sans’s eyes had seemed even darker these last few days. Determined as he was not to pry, Grillby risked a glance at Papyrus and couldn’t help but be struck by the expression of taut uncertainty on the younger monster’s face. Grillby might have his own quiet concerns, but Papyrus was Sans’s brother.

“Would you like to stay a few more minutes?” he asked, pitching his request to be as mild as possible. “Sans looks like he could use the extra sleep.”

Chances were Sans wouldn’t even wake up when Papyrus inevitably tucked him under his arm and carried him home. He frequently didn’t.

“Impossible. He sleeps all the time. Surely he doesn’t need any more,” Papyrus said, trying to affect a scowl, but there was a more heart-aching expression poorly concealed behind it. Surprisingly, he chose to sit anyway…or maybe not so surprising. Grillby knew what loneliness looked like. Despite all his enthusiasm and energy and dedication, at the end of the day, Papyrus really only had Sans. Sans, who to all accounts spend the great portion of his day working, avoiding working, sleeping or just strangely absent.

Although no one could deny how devoted Sans was to his brother. Even without the gossip that circulated in his bar, Grillby had seen enough with his own eyes how Sans doted on Papyrus, indulging him, teasing him, encouraging him. The only thing Sans bragged about was his brother. The highest merit he was willing to accredit himself was whenever he was able to give Papyrus something that made his brother smile, like the dramatic looking costume he now wore as his everyday uniform.

Grillby’s hands tended to keep themselves busy without any need for direction. It was a well-honed habit to keep his business running smoothly and at maximum efficiency, with no moment wasted. He found, without even needing to think about it, that he’d pulled out one of the extra-tall glasses and begun preparing a vanilla milkshake. It was the only item on his menu Papyrus had ever been convinced to indulge in, protesting that he didn’t want to build the same bad habits as his brother.

“Here,” Grillby said, pushing the glass towards Papyrus. The skeleton startled, seeming to have been lost in thought whilst staring at his brother’s slumped form.

Papyrus flustered. “I…I’m afraid I don’t have any money with me…”

Grillby shook his head firmly, refusing to let Papyrus even consider it, but the Skeleton looked unconvinced. Another long held suspicion of Grillby’s, and one he also tried not to think too hard about, was that wherever it was that Sans and Papyrus had come from, there had been a distinct lack of kindness in their lives. It showed in the ways Sans lavished attention on his brother, and how readily Papyrus soaked it up, as if each moment were an unexpected blessing. It showed in the way both skeletons held themselves just a little apart from the rest of the town. It showed in the way Sans refused to talk about himself, no matter how sincerely well-intentioned the questions. It showed in how Papyrus never asked for help, despite how clearly at a loss he was with…well, with most things.

And yet neither of them were hard or bitter or unfriendly. They were just…different. Wary, maybe, or unsure. It was hard to define, and even more difficult to understand, because while the Underground was a hard place to live, the monster community had always been strong and supportive and understanding. If sour old war veterans and hungry orphans could find their place, it seemed odd that a pair of perfectly ordinary skeletons couldn’t.

Then again, ‘ordinary’ might be a bit of a stretch, but that was further conjecture that Grillby refused to ruminate on.

Papyrus was still staring at the glass, his hands gripping the edge of the bar without moving towards it. Grillby allowed himself a silent, inward sigh.

“Sans paid his tab today,” he lied gently, pushing it further across the counter. “So consider it a small celebration. On the house.”

“Oh!” Papyrus exclaimed, sounding more pleased. Sans’s supposed tab was something Papyrus took more seriously than Sans himself. The older skeleton seemed to have realised that Grillby only put things on Sans tab that he never expected to be paid back for, but Papyrus still believe it was some sort of outstanding responsibility. Grillby hadn’t corrected him. That was for Sans to do, and if he hadn’t it meant that he felt comfortable letting Papyrus nag him about something that essentially didn’t exist. Maybe he thought it was funny, or maybe he found Papyrus’s expression of exasperated care comforting.

Or maybe it was because, under the impression of his brother’s supposed accomplishment, Papyrus’s whole demeanour had lightened, and he seemed relieved. Jubilant, even, and the way he looked at the milkshake with tentative wonder and gratitude…well, Grillby could begin to understand why Sans enjoyed spoiling him so much.


	16. StonerBros; Sensitive Bones

**Notes for the Chapter:**

> Anon request for StonerBros [Swap!Papyrus/UT!Sans] with sensitive bones and both of them pining after their own brothers. This one actually ended far too soon (MORE LIKE AN ACTUAL DRABBLE, WOW) not because I don’t adore the pairing, but because it got sad really quickly, and not the fun kind of sad. :( Damnit, boys, I want you to have your happy endings.
> 
> Content Warnings: Underswap!Papyrus/Undertale!Sans with Swapcest and Talecest one-sided and unrequited. Unhealthy coping mechanisms, maybe. Previous mentions of self-harming behaviour (bone-chipping).

Sans pulls off his mitten and offers his hand. The phalanges look especially thin and delicate without their covering, the way Pap knows his own brother’s hands look without the sturdy protection of his gloves.

“Show me what you like,” Sans offers, not hesitantly – he knows what he wants, they both do – but gentle enough not to demand compliance.

It’s not at all the way Blue would ask, his large eyes full of eager impatience, all but crawling into Pap’s lap, ready to begin. It’s nothing like that, but it’s nice all the same. He takes Sans’s hand and brings it to his midriff, lifting his shirt so he can place it on his spine at the base of his ribcage.

“A-ah! Yeah. Right there.” Pap lays down, making himself comfortable against the scrunched sheets. He places his fingers over Sans’s and guides them into curling around his vertebrae, letting them delve into the softer cartilage between the joints. He squeezes, stealing a glance at Sans’s face. It’s flushed blue with a hazy tinge of magic. His eye-lights are larger than usual, too, bright with anticipation and if he squints a little he can imagine that breathless, blissful expression on Blue’s face instead.

“Here too,” he says, loosening his grip so that he can gently pull Sans’s hand further into his ribcage. On the underside, hidden from view, there’s some rough scar tissue from where he’d once been stupid and desperate enough to chip away at the bones, but never where his brother might see it. Sans feels this, his teeth parting a little, but there’s no judgement in his expression. Pap wonders if he maybe has scars to match. He’ll have to find out later.

He presses the tips of Sans’s fingers into the cratered surface, and surprises himself with a low groan. He’d forgotten how good that had felt, once upon a time; the sharp pain of scratching and plucking away at the bone combined with a deep-seated gratification. He’d almost convinced himself the latter was just an illusion conjured up by his sick imagination, trying to excuse away the awful, destructive habit, but fresh experience tells him otherwise. He encourages Sans to press harder, guiding the other to paw and rub and scrape at the scars. Sans does, his other hand finding an anchor up near Pap’s sternum to give him more leverage as he claws at the bone.

“Oh Pap,” he breathes softly, eyes closing, and then, rocking forward, “Papyrus!”

There’s a subtle distinction between when it’s _his_ name Sans is saying, and when it’s his brother’s. Pap can hear it, but he’s not terribly offended. He thinks of his own brother as well, and he’s definitely stuttered out the wrong name in the heat of passion. They’re both understanding enough not to mention when it happens.


End file.
